msem-instigator

As long as you control three or more artifacts, Treasury Master gets +2/+0 and has slipstream. (This creature can't be blocked as long as only creatures with slipstream are attacking.)

When Trench Breaker enters, put target creature on top of its owner's library.

Hexproof
Whenever this creature transforms into Tsunami Titan or attacks, you may return target creature to its owner's hand.

Hexproof

Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)
When Tutorial Boss enters, create a 1/1 blue Pirate creature token.

{1}{U}: Twilight Privateer voyages. (If it isn't blocking or targeted by another spell or ability, it phases out.)
Whenever Twilight Privateer phases in, up to one other target creature voyages.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
{1}{B}, Sacrifice a creature: Put a +1/+1 counter on Twisted Cultist.

Creatures you control dying cause abilities of that creature to trigger as though that creature entered.
{2}{W}{B}, Sacrifice another creature: Destroy target nonland permanent.

Tyrant of the Depths has hexproof as long as it's untapped.
Whenever you cycle Tyrant of the Depths or it attacks, tap target nonland permanent you don't control and put a stun counter on it.
Basic landcycling {1}{U} ({1}{U}, Discard this card: Search your library for a basic land card, reveal it, and put it into your hand, then shuffle.)

If a creature card would be put into an opponent's graveyard from anywhere, instead exile it, then copy it. You may cast the copy. (You still pay its costs, including color. Copies of permanents enter as tokens.)

Hexproof
When Uncharted Leviathan enters, target creature can't be blocked this turn.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)

Undine Coven gets +1/+1 for each other Merfolk you control.
Whenever you cast a noncreature spell, Undine Coven deals 1 damage to target player or planeswalker.

Whenever one or more creatures you control deal combat damage to a player, that player discards a card. Then that player may discard another card. If they don't, create two 2/1 black Nightmare creature tokens with “This creature can't block.”
Fleeting {1}{B}{B} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

Trample
Whenever Unruly Cannoneer crews a Vehicle, that Vehicle gets +1/+1 and gains trample until end of turn.

First mate—There are four or fewer different mana costs among nonland cards in your starting deck. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
First strike
Each spell your opponents cast that would cost less than three mana to cast costs {1} more to cast.

Whenever Veiled Charmer attacks, target creature blocks it this turn if able.

Veiled Merfolk can't be blocked by creatures with greater power.
When Veiled Merfolk enters, mill a card.

{T}: Add {C}. Spend this mana only to cast an instant or sorcery spell or activate an ability.
{2}{U}: Move a counter from target creature onto another target creature.

Defender
Venerable Loremaster can attack as though it didn't have defender if it's in a pack. (Two or more creatures you control with equal power are in a pack.)

Flying
Whenever Venerated Sanctity deals combat damage to a player, put a faith counter on it. Then you may pay {X}{W} and sacrifice Venerated Sanctity. When you do, exile target nonland permanent with mana value less than or equal to X plus the number of faith counters on Venerated Sanctity.

({T}: Add {B}, {G}, or {U}.)
Verdant Dominion enters tapped.

Whenever you cast your second spell each turn, create a 1/1 blue Jellyfish Spirit creature token with flying.

When Volaris Tideshaper enters, look at the top four cards of your library. Put one of those cards into your hand. and the rest on the bottom of your library in a random order.
Whenever you cast a noncreature spell, Volaris Tideshaper can't be blocked this turn.

Whenever Wakeborne Kraken or another Kraken, Leviathan, Octopus, or Serpent you control enters, you may return target creature an opponent controls to its owner's hand.
Whenever a creature an opponent controls leaves the battlefield, if it didn't die, draw a card.